FOCAL TO BILATERAL TONIC-CLONIC SEIZURE

A focal seizure may spread to involve wider brain networks, resulting in a focal to bilateral tonic-clonic
seizure. This was previously known as a 'secondary generalized seizure'. Consciousness is impaired. Motor
components in such a situation include tonic and clonic features. This type of seizure may follow after other
focal seizures types, such as focal motor seizures,
focal cognitive seizures,
focal sensory seizures or
focal impaired awareness seizures.
Alternatively, the spread in brain networks may be so rapid that no preceding focal
seizure type is identified. The focal to bilateral tonic-clonic seizure may be differentiated from the
generalised tonic-clonic seizure
on the basis of other evidence that supports a focal epilepsy/etiology, or
there may be asymmetry seen in the focal to bilateral tonic-clonic seizure (such as head/eye version to one
side, asymmetric amplitude to the motor features), and this asymmetry is seen consistently from seizure to
seizure.